diff options
| -rw-r--r-- | share/man/man4/sa.4 | 66 | ||||
| -rw-r--r-- | sys/cam/scsi/scsi_sa.c | 117 | ||||
| -rw-r--r-- | sys/kern/kern_physio.c | 41 | ||||
| -rw-r--r-- | sys/sys/conf.h | 1 | ||||
| -rw-r--r-- | sys/sys/param.h | 2 |
5 files changed, 221 insertions, 6 deletions
diff --git a/share/man/man4/sa.4 b/share/man/man4/sa.4 index eae3bf5..aa72f68 100644 --- a/share/man/man4/sa.4 +++ b/share/man/man4/sa.4 @@ -25,7 +25,7 @@ .\" .\" $FreeBSD$ .\" -.Dd June 6, 1999 +.Dd August 23, 2013 .Dt SA 4 .Os .Sh NAME @@ -159,6 +159,70 @@ of 0. (As above, if the file mark is never read, it remains for the next process to read if in no-rewind mode.) .El +.Sh BLOCK SIZES +By default, the driver will NOT accept reads or writes to a tape device that +are larger than may be written to or read from the mounted tape using a single +write or read request. +Because of this, the application author may have confidence that his wishes +are respected in terms of the block size written to tape. +For example, if the user tries to write a 256KB block to the tape, but the +controller can handle no more than 128KB, the write will fail. +The previous +.Fx +behavior, prior to +.Fx +10.0, +was to break up large reads or writes into smaller blocks when going to the +tape. +The problem with that behavior, though, is that it hides the actual on-tape +block size from the application writer, at least in variable block mode. +.Pp +If the user would like his large reads and writes broken up into separate +pieces, he may set the following loader tunables. +Note that these tunables WILL GO AWAY in +.Fx 11.0 . +They are provided for transition purposes only. +.Bl -tag -width 12 +.It kern.cam.sa.allow_io_split +.Pp +This variable, when set to 1, will configure all +.Nm +devices to split large buffers into smaller pieces when needed. +.It kern.cam.sa.%d.allow_io_split +.Pp +This variable, when set to 1, will configure the given +.Nm +unit to split large buffers into multiple pieces. +This will override the global setting, if it exists. +.El +.Pp +There are several +.Xr sysctl 8 +variables available to view block handling parameters: +.Bl -tag -width 12 +.It kern.cam.sa.%d.allow_io_split +.Pp +This variable allows the user to see, but not modify, the current I/O split +setting. +The user is not permitted to modify this setting so that there is no chance +of behavior changing for the application while a tape is mounted. +.It kern.cam.sa.%d.maxio +.Pp +This variable shows the maximum I/O size in bytes that is allowed by the +combination of kernel tuning parameters (MAXPHYS, DFLTPHYS) and the +capabilities of the controller that is attached to the tape drive. +Applications may look at this value for a guide on how large an I/O may be +permitted, but should keep in mind that the actual maximum may be +restricted further by the tape drive via the +.Tn SCSI +READ BLOCK LIMITS command. +.It kern.cam.sa.%d.cpi_maxio +.Pp +This variable shows the maximum I/O size supported by the controller, in +bytes, that is reported via the CAM Path Inquiry CCB (XPT_PATH_INQ). +If this is 0, that means that the controller has not reported a maximum I/O +size. +.El .Sh FILE MARK HANDLING The handling of file marks on write is automatic. If the user has diff --git a/sys/cam/scsi/scsi_sa.c b/sys/cam/scsi/scsi_sa.c index f9b0872..6b941e0 100644 --- a/sys/cam/scsi/scsi_sa.c +++ b/sys/cam/scsi/scsi_sa.c @@ -43,6 +43,8 @@ __FBSDID("$FreeBSD$"); #include <sys/mtio.h> #ifdef _KERNEL #include <sys/conf.h> +#include <sys/sysctl.h> +#include <sys/taskqueue.h> #endif #include <sys/fcntl.h> #include <sys/devicestat.h> @@ -223,6 +225,8 @@ struct sa_softc { u_int32_t max_blk; u_int32_t min_blk; u_int32_t maxio; + u_int32_t cpi_maxio; + int allow_io_split; u_int32_t comp_algorithm; u_int32_t saved_comp_algorithm; u_int32_t media_blksize; @@ -268,6 +272,10 @@ struct sa_softc { open_rdonly : 1, /* open read-only */ open_pending_mount : 1, /* open pending mount */ ctrl_mode : 1; /* control device open */ + + struct task sysctl_task; + struct sysctl_ctx_list sysctl_ctx; + struct sysctl_oid *sysctl_tree; }; struct sa_quirk_entry { @@ -426,6 +434,22 @@ static int sardpos(struct cam_periph *periph, int, u_int32_t *); static int sasetpos(struct cam_periph *periph, int, u_int32_t *); +#ifndef SA_DEFAULT_IO_SPLIT +#define SA_DEFAULT_IO_SPLIT 0 +#endif + +static int sa_allow_io_split = SA_DEFAULT_IO_SPLIT; + +/* + * Tunable to allow the user to set a global allow_io_split value. Note + * that this WILL GO AWAY in FreeBSD 11.0. Silently splitting the I/O up + * is bad behavior, because it hides the true tape block size from the + * application. + */ +TUNABLE_INT("kern.cam.sa.allow_io_split", &sa_allow_io_split); +static SYSCTL_NODE(_kern_cam, OID_AUTO, sa, CTLFLAG_RD, 0, + "CAM Sequential Access Tape Driver"); + static struct periph_driver sadriver = { sainit, "sa", @@ -1448,6 +1472,49 @@ saasync(void *callback_arg, u_int32_t code, } } +static void +sasysctlinit(void *context, int pending) +{ + struct cam_periph *periph; + struct sa_softc *softc; + char tmpstr[80], tmpstr2[80]; + + periph = (struct cam_periph *)context; + /* + * If the periph is invalid, no need to setup the sysctls. + */ + if (periph->flags & CAM_PERIPH_INVALID) + goto bailout; + + softc = (struct sa_softc *)periph->softc; + + snprintf(tmpstr, sizeof(tmpstr), "CAM SA unit %d", periph->unit_number); + snprintf(tmpstr2, sizeof(tmpstr2), "%u", periph->unit_number); + + sysctl_ctx_init(&softc->sysctl_ctx); + softc->sysctl_tree = SYSCTL_ADD_NODE(&softc->sysctl_ctx, + SYSCTL_STATIC_CHILDREN(_kern_cam_sa), OID_AUTO, tmpstr2, + CTLFLAG_RD, 0, tmpstr); + if (softc->sysctl_tree == NULL) + goto bailout; + + SYSCTL_ADD_INT(&softc->sysctl_ctx, SYSCTL_CHILDREN(softc->sysctl_tree), + OID_AUTO, "allow_io_split", CTLTYPE_INT | CTLFLAG_RDTUN, + &softc->allow_io_split, 0, "Allow Splitting I/O"); + SYSCTL_ADD_INT(&softc->sysctl_ctx, SYSCTL_CHILDREN(softc->sysctl_tree), + OID_AUTO, "maxio", CTLTYPE_INT | CTLFLAG_RD, + &softc->maxio, 0, "Maximum I/O size"); + SYSCTL_ADD_INT(&softc->sysctl_ctx, SYSCTL_CHILDREN(softc->sysctl_tree), + OID_AUTO, "cpi_maxio", CTLTYPE_INT | CTLFLAG_RD, + &softc->cpi_maxio, 0, "Maximum Controller I/O size"); + +bailout: + /* + * Release the reference that was held when this task was enqueued. + */ + cam_periph_release(periph); +} + static cam_status saregister(struct cam_periph *periph, void *arg) { @@ -1455,6 +1522,7 @@ saregister(struct cam_periph *periph, void *arg) struct ccb_getdev *cgd; struct ccb_pathinq cpi; caddr_t match; + char tmpstr[80]; int i; cgd = (struct ccb_getdev *)arg; @@ -1509,21 +1577,55 @@ saregister(struct cam_periph *periph, void *arg) XPORT_DEVSTAT_TYPE(cpi.transport), DEVSTAT_PRIORITY_TAPE); /* - * If maxio isn't set, we fall back to DFLTPHYS. If it is set, we - * take it whether or not it's larger than MAXPHYS. physio will - * break it down into pieces small enough to fit in a buffer. + * Load the default value that is either compiled in, or loaded + * in the global kern.cam.sa.allow_io_split tunable. + */ + softc->allow_io_split = sa_allow_io_split; + + /* + * Load a per-instance tunable, if it exists. NOTE that this + * tunable WILL GO AWAY in FreeBSD 11.0. + */ + snprintf(tmpstr, sizeof(tmpstr), "kern.cam.sa.%u.allow_io_split", + periph->unit_number); + TUNABLE_INT_FETCH(tmpstr, &softc->allow_io_split); + + /* + * If maxio isn't set, we fall back to DFLTPHYS. Otherwise we take + * the smaller of cpi.maxio or MAXPHYS. */ if (cpi.maxio == 0) softc->maxio = DFLTPHYS; + else if (cpi.maxio > MAXPHYS) + softc->maxio = MAXPHYS; else softc->maxio = cpi.maxio; /* + * Record the controller's maximum I/O size so we can report it to + * the user later. + */ + softc->cpi_maxio = cpi.maxio; + + /* + * By default we tell physio that we do not want our I/O split. + * The user needs to have a 1:1 mapping between the size of his + * write to a tape character device and the size of the write + * that actually goes down to the drive. + */ + if (softc->allow_io_split == 0) + softc->si_flags = SI_NOSPLIT; + else + softc->si_flags = 0; + + TASK_INIT(&softc->sysctl_task, 0, sasysctlinit, periph); + + /* * If the SIM supports unmapped I/O, let physio know that we can * handle unmapped buffers. */ if (cpi.hba_misc & PIM_UNMAPPED) - softc->si_flags = SI_UNMAPPED; + softc->si_flags |= SI_UNMAPPED; softc->devs.ctl_dev = make_dev(&sa_cdevsw, SAMINOR(SA_CTLDEV, 0, SA_ATYPE_R), UID_ROOT, GID_OPERATOR, @@ -1586,6 +1688,13 @@ saregister(struct cam_periph *periph, void *arg) cam_periph_lock(periph); /* + * Bump the peripheral refcount for the sysctl thread, in case we + * get invalidated before the thread has a chance to run. + */ + cam_periph_acquire(periph); + taskqueue_enqueue(taskqueue_thread, &softc->sysctl_task); + + /* * Add an async callback so that we get * notified if this device goes away. */ diff --git a/sys/kern/kern_physio.c b/sys/kern/kern_physio.c index ab9c344..88cd0cf 100644 --- a/sys/kern/kern_physio.c +++ b/sys/kern/kern_physio.c @@ -54,6 +54,36 @@ physio(struct cdev *dev, struct uio *uio, int ioflag) dev->si_iosize_max = DFLTPHYS; } + /* + * If the driver does not want I/O to be split, that means that we + * need to reject any requests that will not fit into one buffer. + */ + if ((dev->si_flags & SI_NOSPLIT) && + ((uio->uio_resid > dev->si_iosize_max) || + (uio->uio_resid > MAXPHYS) || + (uio->uio_iovcnt > 1))) { + /* + * Tell the user why his I/O was rejected. + */ + if (uio->uio_resid > dev->si_iosize_max) + printf("%s: request size %zd > si_iosize_max=%d, " + "cannot split request\n", devtoname(dev), + uio->uio_resid, dev->si_iosize_max); + + if (uio->uio_resid > MAXPHYS) + printf("%s: request size %zd > MAXPHYS=%d, " + "cannot split request\n", devtoname(dev), + uio->uio_resid, MAXPHYS); + + if (uio->uio_iovcnt > 1) + printf("%s: request vectors=%d > 1, " + "cannot split request\n", devtoname(dev), + uio->uio_iovcnt); + + error = EFBIG; + goto doerror; + } + for (i = 0; i < uio->uio_iovcnt; i++) { while (uio->uio_iov[i].iov_len) { bp->b_flags = 0; @@ -83,6 +113,17 @@ physio(struct cdev *dev, struct uio *uio, int ioflag) */ iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK; if ((bp->b_bcount + iolen) > bp->b_kvasize) { + /* + * This device does not want I/O to be split. + */ + if (dev->si_flags & SI_NOSPLIT) { + printf("%s: request ptr %#jx is not " + "on a page boundary, cannot split " + "request\n", devtoname(dev), + (uintmax_t)bp->b_data); + error = EFBIG; + goto doerror; + } bp->b_bcount = bp->b_kvasize; if (iolen != 0) bp->b_bcount -= PAGE_SIZE; diff --git a/sys/sys/conf.h b/sys/sys/conf.h index fcce859..e9a2f55 100644 --- a/sys/sys/conf.h +++ b/sys/sys/conf.h @@ -62,6 +62,7 @@ struct cdev { #define SI_DUMPDEV 0x0080 /* is kernel dumpdev */ #define SI_CLONELIST 0x0200 /* on a clone list */ #define SI_UNMAPPED 0x0400 /* can handle unmapped I/O */ +#define SI_NOSPLIT 0x0800 /* I/O should not be split up */ struct timespec si_atime; struct timespec si_ctime; struct timespec si_mtime; diff --git a/sys/sys/param.h b/sys/sys/param.h index d5905fe..67f4835 100644 --- a/sys/sys/param.h +++ b/sys/sys/param.h @@ -58,7 +58,7 @@ * in the range 5 to 9. */ #undef __FreeBSD_version -#define __FreeBSD_version 1000048 /* Master, propagated to newvers */ +#define __FreeBSD_version 1000049 /* Master, propagated to newvers */ /* * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD, |
